Disposable underpants and method of continuously producing the same

ABSTRACT

Disposable underpants  1  according to the invention has an improved sealability at the crotch of user by providing a fitting elastic member  55  and has an absorbent core  7  having an improved shape retention by providing a first nonwoven fabric  73  as an intermediate layer inside the absorbent core  7  and adhering it to the upper and lower layers thereof. Since the absorbent core needs not be heated, inexpensive disposable underpants can be produced. Further, according to an inventive production method, a step of adhering elastic members to an outer sheet  2  and a step of producing inner absorbent members  6  are separately performed, and no heating treatment is performed in the absorbent core production step. Accordingly, the disposable underpants can be produced at a remarkably higher speed.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to disposable underpants havingsuch a shape that a waist-opening and a pair of leg-openings areprovided and left and right sides are bonded in advance, and includingan absorbent core which has an excellent shape retention and is easilyproducible, and a method for continuously producing such disposableunderpants.

[0002] Since disposable underpants commercially available at present areproduced under a condition that a user walks and makes physical motionswhile wearing them, an absorbent core is required to have a high shaperetention.

[0003] Accordingly, in the prior art, a thermoplastic resin in the formof fibers and particles is mixed as a shape retaining material inaddition to pulp fibers and super absorbent polymer. particles. Morespecifically, if such an absorbent core is heated, this thermoplasticmaterial is melted to adhere to the pulp fibers and the super absorbentparticles. Thus, the pulp fibers are adhered to each other or adhered tothe super absorbent polymer particles after a heating treatment, therebyimproving the shape retention of the absorbent core. Further, the softand bulky absorbent core can be effectively maintained thin by themixing of the thermoplastic resin and the heating adhesion treatment.

[0004] However, if the thermoplastic resin fibers, particles, etc. arenot uniformly dispersed, i.e. concentrate in several locations withoutbeing uniformly dispersed in the absorbent core, this causes such aproblem that portions of the absorbent core where the thermoplasticresin is concentrated hinder the dispersion and permeation of urineand/or prevent the super absorbent polymer particles from swelling uponabsorbing water, thereby reducing an absorbing speed of liquid bodilywastes.

[0005] In order to produce the above absorbent core, an oven for heatingan absorbent core obtained by laminating fibers needs to be prepared. Acirculating hot blast oven is generally used as such an oven, However,it is difficult for the hot blast to reach the inside of the absorbentcore obtained by laminating fibers to a thickness of about 10 mm, andthe absorbent core has to be passed through the oven over an extendedtime in order to heat it until the inside thereof reaches a meltingtemperature of the thermoplastic resin. In order to extend the passingtime in the oven, the oven itself may be enlarged. However, this resultsin a large-scale facility and is disadvantageous in terms of productioncost. As a result, the passing speed of the absorbent core in the ovenhas to be slowed, which stands as a hindrance to an improvement inproduction efficiency.

[0006] On the other hand, the conventional disposable underpants aremade of nonwoven fabric and others, also elastic members in the form ofthreads or strips (made of natural rubber, polyurethane, polyolefinelastomer, etc.) are provided near and around the waist-opening and thepair of leg-openings. Even if stretchable gathers are formed only aroundthese openings , the disposable underpants cannot be worn while ensuringa sufficient sealability. Particularly, the disposable underpantsprovided with a bulky absorbent core does not fit a user at the lowerabdomen and the buttocks and bulges out there. For example, if a personhaving a light problem of incontinence wears a usual garment (trousersor skirt) over disposable underpants, the disposable underpants causehis or her waist line to bulge out, which is not a preferableappearance. In view of the user's psychology, it is naturally demandedto improve the disposable underpants to have such a shape with whichnobody would notice that the user is wearing them. However, if a smallabsorbent pad is used so that nobody would notice, a urine leak mayoccur. Even if no urine leak actually occurs, users have refrained fromgoing out due to an anxiety that they might have a urine leak.

[0007] A first object of the present invention is to produce disposableunderpants provided with an absorbent member which is so constructed asto have a good shape retention without mixing thermoplastic resin fibersand particles into pulp fibers and heating them. A second object of thepresent invention is to provide disposable underpants which fit a usersufficiently and is unlikely to let other people notice that the user iswearing them.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to disposable underpants havingone waist-opening and a pair of leg-opening, having elastic membersprovided near the edges of the waist-and leg-openings and having theopposite sides thereof banded, comprising an outer sheet and an innerabsorbent member, wherein:

[0009] the outer sheet is provided with a waist elastic member, legelastic members and a fitting elastic member provided betweenthe,waist-elastic member and the leg elastic members, the fittingelastic member being comprised of a plurality of thread-like elasticmaterials in parallel with the waist elastic member,

[0010] the inner absorbent member includes a permeable top sheet, animpermeable back sheet and an absorbent core accommodated between thetop and back sheets, and

[0011] the absorbent core includes an upper layer made of a mixture ofpulp fibers and super absorbent polymer particles, an intermediate layerprovided with a first nonwoven fabric, and a lower layer made of amixture of pulp fibers and super absorbent polymer particles, theintermediate layers being adhered to the upper and lower layers by anadhesive.

[0012] Further, a method for continuously producing disposableunderpants comprises the steps of:

[0013] adhering waist elastic members, leg elastic members and fittingelastic members to a continuous web of an outer sheet,

[0014] producing absorbent cores by adhering upper layers made of aMixture of pulp fibers and super absorbent polymer particles and lowerlayers made of a mixture of pulp fibers and super absorbent polymerparticles to the upper and lower surfaces of first nonwoven fabric ofintermediate layers by an adhesive,

[0015] producing inner absorbent members using the absorbent cores,

[0016] forming a laminated assembly by adhering the inner absorbentmembers at specified intervals onto the continuous web of the outersheet having the respective elastic members adhered thereto,

[0017] folding the laminated assembly in two with the inner absorbentmembers faced inward,

[0018] providing cut-away portions for the leg-openings in the laminatedassembly folded in two,

[0019] bonding the opposite sides of the laminated assembly folded intwo, and

[0020] separating the laminated assembly having its opposite sidesadhered at specified intervals to form the individual disposableunderpants.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a front view of disposable underpants according to theinvention,

[0022]FIG. 2 is a developed plan view partly in section of thedisposable underpants of FIG. 1, FIG. 3 is a section showing anembodiment of an inner absorbent member,

[0023] FIGS. 4(a) to 4(c) are plan views showing applied states ofadhesive,

[0024]FIG. 5 is a plan view of an absorbent core,

[0025]FIG. 6 is a section of the disposable underpants along theirlongitudinal direction,

[0026]FIG. 7 is a front view showing another embodiment of theinvention,

[0027]FIG. 8 is a plan view showing how leg elastic members areprovided,

[0028]FIG. 9 is a perspective view showing a production method accordingto the invention, and

[0029]FIG. 10 is a plan view showing the production method according tothe invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

[0030] One embodiment of disposable underpants according to theinvention is described in detail with reference to FIGS. 1 to 8.Disposable underpants 1 are shaped by an outer sheet 2 to have awaist-opening 3 at the top and a pair of leg-openings 4,4 as shown inFIG. 1. Front and rear parts of the disposable underpants 1 are bondedby left and right joint portions 5. In vicinity of the waist-opening 3and the leg-openings 4,4, a plurality of thread-shaped elastic members(polyurethane, polyolefin elastomer, rubber, etc.) are provided as awaist elastic members 53 and leg elastic members 54. These elasticmembers 53, 54 form waist stretchable gathers and leg stretchablegathers. Between the waist elastic member 53 and the leg elastic members54, a plurality of thread-like elastic materials are provided as afitting elastic member 55 in parallel to the waist elastic members 53over the entire circumference of the disposable underpants 1. By thepresence of the fitting elastic member 55, the disposable underpants 1can fit the lower abdomen and buttocks of the user with an improvedsealability.

[0031] Inside the disposable underpants 1 is mounted an inner absorbentmember 6. An absorbent core 7 is contained inside the inner absorbentmember 6 for absorbing bodily wastes of the user such as urine and loosestool. The positions of the fitting elastic member 55 and the absorbentcore 7 are preferably adjusted so that a bottom end 55 e of the fittingelastic member 55 is located more toward a waist-opening end 3 e than alongitudinal end 7 e of the absorbent care 7. If the fitting elasticmember 55 and the absorbent core 7 overlap, the stretching force of thefitting elastic member 55 may be hindered since the absorbent core 7 isrelatively hard. Further, by limiting the position of the bulkyabsorbent core 7 to the one below the crotch which is necessary toabsorb bodily wastes, the thickness of the disposable underpants I atthe lower abdomen and the buttocks which tend to bulge out after thedisposable underpants 1 are worn can be reduced. As a result, thedisposable underpants 1 can be made unnoticeable.

[0032]FIG. 2 is a development of the disposable underpants 1 of FIG. 1.The disposable underpants 1 are substantially comprised of the outersheet 2 and the inner absorbent member 6. The inner absorbent member 6is bonded in the middle of the outer sheet 2, and joint margins 5 a, 5 aat the opposite sides of a section B of the outer sheet 2 correspondingto the rear side of the disposable underpants 1 and joint margins 5 b, 5b at the opposite sides of a section F of the outer sheet 2corresponding to the front side of the disposable underpants 1 are puttogether and joined, thereby obtaining the disposable underpants 1having a shape as shown in FIG. 1. The outer sheet 2 is comprised of anoutermost nonwoven fabric 21 and an inner nonwoven fabric 22. In anexample of FIG. 2, the outermost nonwoven fabric 21 of the outer sheet 2extends longer than the inner nonwoven fabric 22 at the waist-openingend 3 e, and this projecting portion is turned down onto the innernonwoven fabric 21, thereby forming a turned portion 21 a. The waistelastic member 53 in its stretched state is intermittently adheredbetween the turned portion 21 a and the inner nonwoven fabric 22. Thefitting elastic member 55 and the leg elastic members 54 are providedbetween the outmost nonwoven fabric 21 and the inner nonwoven fabric 22.It should be noted that the waist elastic member 53 may be providedbetween the outermost nonwoven fabric 21 and the inner nonwoven fabric22. In such a case, the turned portion 21 a may or may not be provided.

[0033] Nonwoven fabrics made of cellulose, rayon, acetate, polyethylene,polypropylene, nylon, polyester, acrylic fiber, etc. (hereinafter,nonwoven fabrics are referred to as these nonwoven fabrics) can bepreferably used for the outermost nonwoven fabric 21 and the innernonwoven fabric 22 and others. Nonwoven fabrics to which a waterrepellent treatment is applied may be used. A hot-melt adhesive can beconveniently used to adhere the respective elastic members to therespective nonwoven fabrics.

[0034] The inner absorbent member 6 is comprised of an impermeable backsheet 61 located at the outermost in this member 6, the absorbent core 7and a permeable top sheet 62 to fit a user's skin. The impermeable backsheet 61 may be caused to project at the left and right sides of theabsorbent core 7, and the projecting portions may be turned onto theupper surface of the top sheet 62 as indicated by a hatched portion 61 ain FIG. 2. This prevents urine from leaking through the opposite sidesof the absorbent core 7.

[0035]FIG. 3 is a section showing a preferable embodiment of the innerabsorbent member 6 along its widthwise direction. The absorbent core 7in the inner absorbent member 6 essentially consists of an upper layer71, a lower layer 72 and an intermediate layer 73 including a firstnonwoven fabric. The upper and lower layers 71, 72 are made of a mixtureof pulp fibers and super absorbent polymer particles. The content of thesuper absorbent polymer particles is preferably about 10 to 65% byweight of the entire weight of the absorbing material (a total of theupper and lower layers) in order to rapidly absorb bodily wastes.

[0036] In the example of FIG. 3, a second nonwoven fabric 75 is providedbelow the lower layer 72 and above the impermeable back sheet 61, and atissue 74 is provided above the upper layer 71 and below the top sheet62. The tissue 74 and the upper layer 71; the upper layer 71 and thefirst nonwoven fabric 73; the first nonwoven fabric 73 and the lowerlayer 72; and the lower layer 72 and the second nonwoven fabric 75 arebonded to each other by a hot-melt adhesive or the like, respectively,thereby forming the absorbent core 7 as a whole.

[0037] The upper layer 71 and the first nonwoven fabric 73, and thefirst nonwoven fabric 73 and the lower layer 72 are bonded by applyingthe hot-melt adhesive to the first nonwoven fabric 73. It is preferableto bond them before the hot-melt adhesive solidifies. This is becausethe upper and lower layers 71 and 72 are bonded by the hot-melt adhesivepermeated along the thickness direction of the first nonwoven fabric 73.Since the upper and lower layers 71,72 are firmly bonded to each othervia the first nonwoven fabric 73 in the inventive absorbent core 7, thefirst nonwoven fabric acts as a core member, thereby giving theabsorbent core 7 an excellent shape retention. Further 7 since thehot-melt adhesive permeates through the upper or lower layer to bond thepulp fibers to each other and the pulp fibers and the super absorbentpolymer particles, this is also effective in improving the shaperetention. Accordingly, if the inventive absorbent core constructed asabove is used, it is not necessary to mix thermoplastic resin fibersinto the absorbent core and to heat the absorbent core.

[0038] Further, by turning the side portions of the second nonwovenfabric 75 projecting from the lower layer 72 onto the lower layer 72 orby bending the tissue 74 at the opposite sides of the upper layer 71 andbonding the bent portions, the shape retention of the absorbent core 7can be further improved. Since the tissue 74 and the second nonwovenfabric 75 can be used as a material for wrapping the upper and lowerlayers in a production line for the upper and lower layers 71, 72, theyare useful in preventing the pulp fibers and the super absorbent polymerparticles from being dispersed into a working environment in theproduction line.

[0039] When the upper layer 71, the lower layer 72, the first nonwovenfabric 73 as an intermediate layer, the tissue 74, and the secondnonwoven fabric 75 are bonded by the hot-melt adhesive, it is necessaryto provide unapplied portions of the hot-melt adhesive so as not tohinder the absorption of bodily wastes such as urine and loose stool bythe absorbent core 7. Particularly, unless the unapplied portions areprovided in the first nonwoven fabric 73, it is not preferable since thebodily wastes do not permeates through the lower layer 72. In order toprovide the unapplied portions, the hot-melt adhesive may be appliedsuch that the applied portions form an aggregate of lines such asspirals, a net or irregular lines as shown in FIGS. 4(a), 4(b) and 4(c).It is easy to apply the melted hot-melt adhesive in such a manner as toform an aggregate of lines by applying it by the nozzle coating method,spray coating method, or the like. It should be noted that the hot-meltadhesive may he applied in strips or dots.

[0040] The upper layer 71 of the absorbent core 7 is narrowed at theleft and right sides in the middle with respect to its longitudinaldirection to form narrow parts 47,47 so that it has a substantiallysandglass-like shape as shown in FIG. 5. These narrow parts 47, 47 areadapted so as not to hinder the stretchability of the leg elasticmembers 54,54 (see FIG. 1) of the leg-openings (identified by 4 in FIG.1). Although the lower layer 72 may have the same shape as the upperlayer 71, it preferably has a rectangular shape whose width is slightlysmaller than that of the upper layer 71. Since the bodily wastes aremostly absorbed by the upper layer 71, the lower layer 72 may beprovided as an auxiliary absorbing member in the case that a largeamount of urine needs to be absorbed. Thus, the lower layer 72 can bemade smaller than the upper layer 71. The smaller lower layer 72 reducesthe bulging-out of the disposable underpants at the crotch, which makesthe disposable underpants unnoticeable in appearance after being wornand prevents the stretchability of the leg gathers from being hindered.Since the human legs are normally thicker at the thighs near the crotchthan at the crotch, the absorbent core is less likely to be worn ortwisted due to the user's movements (rubbing of the thighs against eachother) to have an improved shape retention if the lower layer 72 is madesmaller.

[0041] The absorbent core 7 constructed as above is suitably bondedbetween the impermeable back sheet 61 and the permeable top sheet 62 asshown in FIG. 3. Of course, the top sheet 62 and the tissue 74 (theupper layer 71 when no tissue is provided) are so bonded as not tohinder the water permeability. The bottom end of raised gathers 81 maybe bonded to the upper surface of the turned portion 61 a which is aportion of the back sheet 61 turned onto the upper surface of the topsheet 62. By providing thread-shaped elastic members 82 at the leadingends of the raised gathers 81, the raised gathers 81 rise against theuser's skin, with the result that the flow of the urine can beeffectively stopped.

[0042]FIG. 6 is a section of the disposable underpants along thelongitudinal direction showing a preferable embodiment near thewaist-opening. The outermost nonwoven fabric 21 is turned toward theinner nonwoven fabric 22 at the waistopening edge, thereby forming theturned portion 21 a as also shown in FIG. 2. The waist elastic member 53is provided between the turned portion 21 a and the inner nonwovenfabric 22. The fitting elastic member 55 is provided between theoutermost nonwoven fabric 21 and the inner nonwoven fabric 22 such thatits bottom end 55 e is located more toward the waist-opening end (upperside in FIG. 6) than the longitudinal end 7 e of the absorbent core 7 inthe inner absorbent member 6. In the example of FIG. 6, a separatenonwoven fabric 23 is provided from below the turned portion 21 a to theupper end of the inner absorbent member 6. This nonwoven fabric 23 isprovided if necessary. If the nonwoven fabric 23 made of water repellentfibers is used or a water repellent treatment is applied to make thenonwoven fabric water impermeable, the penetration of the urine intoportions of the disposable underpants outside the inner absorbent member6 can be prevented.

[0043] In all of the above examples, the positions of the fittingelastic member 55 and the absorbent core 7 in the absorbent member 6 areadjusted such that the bottom end 55 e of the fitting elastic member 55is located more toward the waist-opening end than the longitudinal end 7e of the absorbent core 7, i.e. the fitting elastic member 55 and theabsorbent core 7 do not overlap. However, the fitting elastic member 55and the absorbent core 7 may overlap.

[0044] For example, FIG. 7 shows an example of disposable underpants inwhich the inner absorbent member 6 and the absorbent core 7 are longerthan those of FIG. 1. The same elements as those shown in FIG. 1 are notshown in FIG. 7 There is an overlapping area (hatched area X) of thefitting elastic member 55 (thread-like fitting elastic materials in theorder of ten are provided between the upper end 55 ue and the bottom end55 e, but are not shown in FIG. 7) and the absorbent core 7. Since theabsorbent core 7 is harder than the nonwoven fabric, the action of thestretchability of the fitting elastic materials on the area X does notimprove the sealability of the disposable underpants, but may causes theabsorbent core 7 to be worn out. However, it is complicated to cut onlythe fitting elastic materials overlapping with the absorbent core 7during the production. Therefore, it is preferable to bond the fittingelastic member 55 to the outer sheet 2 without being stretched in thearea X. By adopting this method, the fitting elastic member 55 can becontinuously provided without being cut in the production line and thereis no bad influence on the absorbent core 7 when the disposableunderpants are worn.

[0045] Independent of whether the fitting elastic member be changedbetween the front and rear sides of the disposable underpants. In thecase of large-size disposable underpants frequently used by peoplehaving large buttocks, sealability can be ensured even if the stretchingforce of the rear side is made weaker than that of the front side, sothat the buttocks are not forcibly tightened. Further, since most of thelean people have small buttocks, it is preferable to substantiallyequally set the stretching forces of the front and rear sides insmall-size disposable underpants. Furthermore, the fitting elasticmember may be provided in different positions(upper and lower portions)at the front and rear sides of the disposable underpants.

[0046]FIG. 8 is a diagram showing how the leg elastic members 54, 54according to the invention are provided. In the front part F of thedisposable underpants, the leg elastic member 54 is comprised of leftand right side portions 54 a, 54 c extending along the edges of theleg-openings 4, 4, and a connecting portion 54 b connecting the leadingends of the side portions 54 a, 54 c, and forms a substantially U-shapedline. The same applies to the rear part B of the disposable underpants.As shown in FIG. 8, the connecting portions 54 b of the front and rearlines of the leg elastic members 54 do not intersect with each other atthe crotch of the disposable underpants. If they intersect at thecrotch, the inner absorbent member 6 is squeezed outward of thedisposable underpants by the stretching forces of the leg elasticmembers 54, 54, resulting in a poor appearance. The positions of thefront and rear U-shaped lines of the connecting portions 54 b where theyare opposed to each other may be displaced to either the front or rearpart of the disposable underpants.

[0047] The spacing between the respective thread-like elastic materialsforming the leg elastic members 54 is narrowest in intermediate portions(S₂) between the side ends of the side portions 54 a (or 54 c) and themiddle portion of the connecting portions 54 b and gradually widenstoward the side ends (S₁) of the side portions and toward the middleportion (S₃) of the connecting portions 54 b. Further, the thread-likeelastic materials are preferably provided such that their stretchingforces are weakest in the intermediate portions between the side ends ofthe side portions 54 a (or 54 c) and the middle portion of theconnecting portions 54 b and gradually become stronger toward the sideends (S₁) of the side portions and toward the middle portion (S₃) of theconnecting portions 54 b. By this construction, the crotch of thedisposable underpants can closely fit the user and does not give anypain to the user by pressing his/or groin.

[0048] The disposable underpants according to the invention are formedinto the shape as shown in FIG. 1 by bonding the joint margins 5 a, 5 bat the opposite sides of the front and rear parts in the development ofFIG. 2. At this time, the joint construction at the opposite sides ofthe disposable underpants is such that the outer sheet 2 in which belaminated three sheets: the outermost nonwoven fabric 21, the innernonwoven fabric 22 and the turned portion 21 a, are laid one overanother are put together in a portion where the turned portion 21 a ofthe outermost nonwoven fabric 21 is present, whereas the outer sheets 2comprised of two sheets: the outermost nonwoven fabric 21 and the innernonwoven fabric 22, are put together in a portion where the turnedportion 21 a is absent (i.e. the crotch side).

[0049] Further, in the disposable underpants constructed as shown inFIG. 6, since the nonwoven fabric 23 is laid in addition to the turnedportion 21 a in some portion of the outer sheet, the outer sheetcomprised of these is bonded. The joint margins at the opposite sides ofthe disposable underpants can be easily bonded using a heat sealer or anultrasonic welding machine. If the bonding force is insufficient, another thermoplastic film, nonwoven fabric, adhesive net, adhesive or thelike may be added between any arbitrary layers to improve the bondingforce.

[0050] As is clear from FIG. 1, most of the inventive disposableunderpants is formed only by the outer sheet made of nonwoven fabrics,and the impermeable sheet (as 61 in FIG.1) which causes sweatiness ispresent only where the inner absorbent member is provided. Therefore,the inventive disposable underpants have an excellent breathability.

[0051] Hereinafter, a method for producing the inventive disposableunderpants is described with reference to FIGS. 9 and 10. According tothe inventive method, the waist elastic member, the leg elastic membersand the fitting elastic member are first provided on the continuous webof the outer sheet. In FIG. 9, continuous elastic strands 153, 154 and155 of the waist elastic member (53) the leg elastic members (54, 54)and the fitting elastic member (55) are applied to a continuous web 121of the outer-nonwoven fabric (21). In this step, a hot-melt adhesive issprayed onto the continues web 121 of the outermost nonwoven fabric (21)and/or the continuous elastic strands 153 to 155 of the respectiveelastic members (53 to 55), the continues elastic strands 153 to 155 areadhered to specified positions of the continues web 121 while beingstretched, a continuous web 122 of the inner nonwoven fabric (22) isplaced on the continuous web 121 having the continuous elastic strands153 to 155 adhered thereto, and these continuous members 121, 153 to155, and 122 are pressed by rollers 10, 10 to adhere to each other. Inorder to provide the leg elastic members (54, 54) in U-shaped line asshown in FIG. 8, support guides (not shown in FIG.6 for the continuouselastic strands 154 are vertically moved in a direction normal to arunning direction while the continuous web 121 is running, so that thecontinuous elastic strands 154 are adhered in a continuous sinusoidalcurve. When the individual disposable-underpants are separated, the legelastic members 54, 54 form U-shaped lines. By this step, a continuousweb 12 of the outer sheet (2) in which the respective elastic membersare provided is formed.

[0052] It should be noted that a step of providing the turned portions21 a of the outermost nonwoven fabric 21 and a step of providing theanother nonwoven fabric 23 can be added.

[0053] Subsequently, the inner absorbent members 6 produced in aseparate step are adhered to the outer sheet continuous web 12. Theseinner absorbent members 6 are produced by a step of producing theabsorbent core by adhering the upper and lower layers made of a mixtureof the pulp fibers and the super absorbent polymer particles to theupper and lower surfaces of the first nonwoven fabric as theintermediate layer, a step of placing the top sheet on the absorbentcore after the absorbent core is placed on the back sheet and rolling upthe opposite sides of back sheet in such a manner as to wrap theabsorbent core and adhering them to the top sheet, and, if desired, astep of adhering the members of the raised gathers. Of course, a step ofadhering the tissues (74) and the second nonwoven fabric (75) shown inFIG. 3 can be added in the step of producing the absorbent core.

[0054] After the inner absorbent members 6 are adhered to the outersheet continuous web 12 at specified intervals, a step of folding thecontinuous web 12 in two with the inner absorbent members 6 facedinward, a step of bonding the opposite sides of disposable underpantsP₁, P₁ along bonding lines AL,AL a step of cutting along cutting linesCL₂ to provide cut-away portions for the leg-openings, and a step ofcutting along cutting lines CL₁ to separate the individual disposableunderpants P₁, P₂ are successively performed. It does not matter whichof the second and the third ones of the above four steps are performedprior to the other. Alternatively, the third step may be provided beforethe first step.

[0055] Since the absorbent cores need not be heated according to theinventive production method, the inner absorbent members can bemanufactured at a high speed. Further, the disposable underpants can becontinuously manufactured at a high speed since the respective elasticmembers are applied in the same direction as the running direction ofthe continuous web of outer sheet and the folding step and the bondingstep do not hinder the running of the continues web of outer sheet.

[0056] Further, according to the inventive production method, it is notnecessary to prepare a producing apparatus for each size. For example,if disposable underpants P₁ having a large waist size W₁ and disposableunderpants P₂ having a small waist size W₂ are produced in the sameproduction line as shown in FIG. 10, it is sufficient to change thepositions of the cutting lines CL₁,CL₃ and the bonding lines AL in FIG.9. More specifically, as seen from FIGS. 9 and 10, a waist-openinglength (2×W₁) of the disposable underpants P₁ is determined by thecutting lines CL₁ indicated by phantom line and the bonding lines AL(solid line) provided inside the cutting lines CL₁, CL₁. Further, theleg-opening length is 2×L₁. The disposable underpants P₂ having asmaller waist width W₂ than W₁ can be easily produced by using thecutting lines CL₃,CL₃ (indicated by dotted line) instead of the cuttinglines CL₁, CL₁, and defining the bonding lines AL₂, AL₂ inside thecutting lines CL₃, CL₃. Since the leg-opening length (2×L₂) of thedisposable underpants P₂ are smaller than that of the disposableunderpants P₁, there can be provided disposable underpants adapted tothe actual situation where people having a slender waist generally haveslender legs.

What is claimed is:
 1. Disposable underpants having one waist-openingand a pair of leg-openings, having elastic members provided near theedges of the waist- and leg-openings and having the opposite sidesthereof bonded, comprising: an outer sheet and an inner absorbentmember, wherein: the outer sheet is provided with a waist elasticmember, leg elastic members and a fitting elastic member providedbetween the waist elastic member and the leg elastic members, thefitting elastic member being comprised of a plurality of thread-likeelastic materials in parallel with the waist elastic member, the innerabsorbent member includes a permeable top sheet, an impermeable backsheet and an absorbent core accommodated between the top and backsheets, and the absorbent core includes an upper layer made of a mixtureof pulp fibers and super absorbent polymer particles, an intermediatelayer provided with a first nonwoven fabric, and a lower layer made of amixture of pulp fibers and super absorbent polymer particles, theintermediate layers being adhered to the upper and lower layers by anadhesive.
 2. Disposable underpants according to claim 1, wherein theabsorbent core further includes a second nonwoven fabric located belowthe lower layer thereof, and a tissue located above the upper layerthereof, the second nonwoven fabric being adhered to the lower layer anda portion of the second nonwoven fabric projecting out from the outerperiphery of the lower layer is turned up onto the lower layer andadhered while being placed to the first nonwoven fabric.
 3. Disposableunderpants according to claim 2, wherein the upper layer of theabsorbent core is formed larger than the lower layer thereof, the upperlayer is formed to have a substantially sandglass-shape having narrowedportions at the left and right sides of a middle portion with respect toits longitudinal direction in its plan view while the lower layer isformed to have a rectangular shape in its plan view, and the upper andlower layers are laid such that a center line of the upper layer withrespect to its widthwise direction and that of the lower layercorrespond with each other.
 4. Disposable underpants according to claim2, wherein the first nonwoven fabric of the intermediate layer of theadhesive unapplied portion, and the adhesive applied portion forms anaggregate of a multitude of lines.
 5. Disposable underpants according toclaim 2, wherein the outer sheet includes an outermost nonwoven fabricand an inner nonwoven fabric, and at least the leg elastic members andthe fitting elastic member are provided between these two nonwovenfabrics.
 6. Disposable underpants according to claim 5, wherein thewaist elastic member is provided between a turned portion formed byturning the outermost nonwoven fabric onto the inner nonwoven fabric atthe waist-opening edge and the inner nonwoven fabric.
 7. Disposableunderpants according to claim 1, wherein the fitting elastic member isprovided more toward the waistopening edge than a longitudinal end ofthe absorbent core of the inner absorbent member, so that the fittingelastic member and the absorbent core do not overlap.
 8. Disposableunderpants according to claim 1, wherein the fitting elastic memberpartly overlaps the absorbent .core of the inner absorbent member, aportion thereof located in the overlapping portion being provided innon-stretched state so as not to contract.
 9. Disposable underpantsaccording to claim 1, wherein the stretching force of the fittingelastic member differs in the front and rear parts of the disposableunderpants.
 10. Disposable underpants according to claim 1, wherein eachleg elastic member is made of a plurality of thread-like elasticmaterials, that thread-like elastic materials are, at the front part ofthe disposal underpants, comprised of left and right side portionsextending along the leg-opening edges of the front part of disposableunderpants and connecting portions connecting the leading ends of theside portions, thereby forming substantially U-shaped lines, whilebeing, at the rear part of the disposable underpants, likewise comprisedof left and right side portions extending along the leg-opening edges ofrear part of the disposable underpants and connecting portionsconnecting the leading ends of the side portions, thereby formingsubstantially u-shaped lines, and the connecting portions of the frontand rear lines do not intersect with each other at the crotch of thedisposable underpants.
 11. Disposable underpants according to claim 10,wherein the spacing between the respective thread-like elastic materialsof each leg elastic member is narrowest at intermediate positionsbetween the side ends of the side portions and the middle of theconnecting portions and gradually widens toward the side ends of theside portions and toward the middle of the connecting portions. 12.Disposable underpants according to claim 10, wherein the stretchingforce of the thread-like elastic materials of the leg elastic membersare weakest at intermediate positions between the side ends of the sideportions and the middle of the connecting portions and gradually becomesstronger toward the side ends of the side portions and toward the middleof the connecting portions.
 13. Disposable underpants according to claim1, wherein the left and right side ends of the impermeable back sheet ofthe inner absorbent member are turned up onto the upper surface of thepermeable top sheet, and raised gathers made of a nonwoven fabric andprovided with a stretchable member are adhered onto the upper surfacesof the turned portions.
 14. Disposable underpants according to claim 1,wherein the left and right sides of the disposable underpants are bondedby putting the outer sheet together and applying heating to melt it. 15.A method for continuously producing disposable underpants according toclaim 1, comprises the steps of: adhering a waist elastic member, legelastic members and a fitting elastic members to a continuous web of anouter sheet, producing an absorbent core by adhering an upper layer madeof a mixture of pulp fibers and super absorbent polymer particles and anlower layer made of a mixture of pulp fibers and super absorbent polymerparticles to the upper and lower surfaces of first nonwoven fabric of anintermediate layer by an adhesive, producing inner absorbent membersusing the absorbent core, forming a laminated assembly by adhering theinner absorbent members at specified intervals onto the continuous webof the outer sheet having the respective elastic members adheredthereto, folding the laminated assembly in two with the inner absorbentmembers faced inward, providing cut-away portions for the leg-openingsin the laminated assembly folded in two, bonding the opposite sides onthe laminated assembly folded in two, and separating the laminatedassembly having its opposite sides adhered at specified intervals toform the individual disposable underpants.
 16. A method according toclaim 15, wherein disposable underpants having different sizes areproduced in the same production line by adjusting the bonding intervalson continuous laminated assembly folded or intervals at which theopposite sides of the disposable underpants are bonded.